To the best of my abilities, I’ve found what I believe to be legit sales for RWBY Vol. 1 - Vol. 8 posters:
RWBY Quad Poster
RWBY Actress Poster
RWBY Vol. 1 Girls Poster
RWBY Vol. 1 Poster
RWBY Vol. 1 Art Poster
RWBY Vol. 2 Poster
RWBY Vol. 3 Poster
RWBY Vol. 4 Girls Poster
RWBY Vol. 5 Poster
RWBY Vol. 6 Poster
RWBY Vol. 7 Poster
RWBY Vol. 8 Poster